Python Coding challenge - Day 603| What is the output of the following Python Code?

 Code Explanation:

1. Importing dropwhile from itertools

from itertools import dropwhile

This line imports the dropwhile function from Python's built-in itertools module.

dropwhile(predicate, iterable) returns an iterator that drops items from the iterable as long as the predicate is true; once it becomes false, it yields every remaining item (including the first one that made the predicate false).

2. Defining a Generator Function stream()

def stream():

    for i in [1, 3, 5, 2, 4]:

        yield i

This defines a generator function named stream.

Inside the function, a for loop iterates over the list [1, 3, 5, 2, 4].

The yield keyword makes this a generator, producing one value at a time instead of all at once.

First yields 1, then 3, then 5, then 2, then 4.

3. Applying dropwhile

dropped = dropwhile(lambda x: x < 4, stream())

dropwhile starts consuming the stream of values only while the condition (x < 4) is True.

The lambda function is lambda x: x < 4, i.e., drop values less than 4.

Let’s go through the values one-by-one:

1 → < 4 → dropped.

3 → < 4 → dropped.

5 → NOT < 4 → stop dropping. Start yielding from here.

So the remaining values to be yielded are: 5, 2, 4.

4. Printing the Result

print(list(dropped))

This converts the dropped iterator into a list and prints it.

From above, we determined the iterator yields: [5, 2, 4].

Output:

[5, 2, 4]

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